A more precise map of the complement genes linked to the human major histocompatibility complex will be constructed since even our own data are contradictory as to the position of the C2/Bf genes. The mouse/human hybrid cells will be studied for factor B production and for C3 synthesis, as well. The latter is of importance because in the mouse C3 is syntenic with the MHC, whereas family studies in man have not shown linkage of C3 with MHC markers. Studies of the molecular basis of C5 deficiency in mice will be performed. Regulation of complement production by human monocytes and breast macrophages will be undertaken. Analysis of production of complement by single cells will be applied to homozygous and heterozygous C4 deficient guinea pigs.